1. Field of the Invention
This invention relates to tube couplers and is particularly although not exclusively applicable to couplers for locking tubes in tap or valve bodies.
2. Background of Prior Art
U.S. Pat. No. 3,653,689 discloses a releasable coupling for a fluid carrying tube comprising a socket having stepped concentric bores, a collar having a conical surface retained in the first bore and a clamping member mounted for axial movement within the collar having a plurality of flexable jaws. The clamping member has an inclined surface to co-operate with the conical surface on the collar to force the jaws inwardly to clamp a tube received in the socket. The outer surface of the collar has a cylindrical guide portion for fitting into a socket in a further body and also has a conical portion which defines a sharp tooth-edged projection to engage and lock the collar in their socket in the body. The collar or cartridge is machined from solid metal and in order to provide the requisite gripping action in the body to withstand the high loads to which the fitting can be subjected, the outer surface of the collar and the conical projection must be machined to a very high degree of accuracy as must the diameter of the bore in the socket or the collar will not be adequately supported in the socket and the conical projection will not have the required degree of grip with the socket to hold the collar in the socket. If the collar has to be extracted from the socket for any reason, for example to enable seals in the collar to be replaced, the conical projection on the outer surface of the collar is almost certain to be damaged and will not provide adequate gripping engagement in the socket if it is re-inserted in the socket. Thus if the collar fails for any reason, it will almost certainly be necessary to replace the collar as well as any other failed component.
It is an object of this invention to provide a tube coupling in which the collar or sleeve can be manufactured without the need for highly accurate machining and which enables the sleeve to be extracted from the body in which it is housed as required and re-inserted without the risk of the gripping engagement of the sleeve in the body being significantly diminished.